1. Field of the Invention
The present invention relates to an encapsulated stator and, more particularly, to a stator including a driving module encapsulated by an encapsulant.
2. Description of the Related Art
FIG. 1 shows a conventional motor stator 8 including a plurality of pole plates 81. Coils 82 are wound around the pole plates 81. The pole plates 81 and the coils 82 are encapsulated by a waterproof encapsulant 83 to provide a sealed structure. Thus, the motor stator 8 is waterproof and moisture-proof. An example of such a motor stator 8 is disclosed in Taiwan Patent No. 1266469 entitled “WATERPROOF STRUCTURE FOR BRUSHLESS MOTOR”.
The motor stator 8 is coupled to a rotor to form a motor. Air gaps exist between a permanent magnet on the rotor and the pole plates 81. When the motor stator 8 is energized to create an alternating magnetic field induced by the permanent magnet, the magnetic lines of force created by the permanent magnet pass through the air gaps and interact with the motor stator 8 to generate a flux linkage, driving the rotor to rotate.
However, the air gaps between the permanent magnet and the pole plates 81 will be too small if the waterproof encapsulant 83 has a large thickness, leading to poor operational efficiency. On the other hand, the encapsulating effect will be adversely affected if the thickness of the waterproof encapsulant 83 is too small, adversely affecting the waterproof effect and the moisture-proof effect of the motor stator 8.
FIG. 2 shows another conventional motor stator 9 including a driving circuit board 91, a stator 92, and a housing 93 to which the driving circuit board 91 and the stator 92 are mounted. A separation sleeve 94 is mounted around the stator 92. The stator 92 and the separation sleeve 94 are encapsulated by a waterproof encapsulant 95 to provide the motor stator 9 with enhanced waterproof effect and enhanced moisture-proof effect. An example of such a motor stator 9 is disclosed in Taiwan Patent No. I323071 entitled “WATERPROOF MOTOR STATOR DEVICE AND METHOD FOR MAKING SAME”.
The separation sleeve 94 mounted around the stator 92 permits an easy mold-removing operation of the motor stator 9. Since the waterproof encapsulant 95 encapsulates both of the stator 92 and the separation sleeve 94, the air gaps between the permanent magnet and the stator 92 are decreased due to the thickness of the separation sleeve 94 and the waterproof encapsulant 95 when the stator 92 is coupled with a rotor to form a motor, resulting in safety risks during operation of the motor. Improvement is, thus, required.